Collapsible drill bit assembly and method of drilling



April 4, 1961 w. H. DE vAAN 2,978,047

COLLAPSIBLE DRILL BIT ASSEMBLY AND METHOD OF DRILLING Filed Dc. 5, 1957 4 Sheets-Sheet l Waller H. 0e vaan INVENTOR.

WWW 15ML@ April 4, V1961 w. H. DE vAAN I 2,978,047

COLLAPSIBLE DRILL BIT ASSEMBLY AND METHOD OF DRILLING 4 Sheets-Sheet 2 Filed Dec. 5, 1957 W- H. DE VAAN L BIT ASSEMBLY AN D METHOD oF DRILLING 4 Sheets-Sheet 5 Wa/fer h'. evaan INVENToR.

April 4, 1961 w. H. DE vAAN 2,973,047

coLLAPsIBLE DRILL BIT ASSEMBLY AND METHOD oF DRILLING Filed Dec. 3, 1957 4 Sheets-Sheet 4 INVENToR.

v@ BY Q as.

aM/WMM ,.f H. DeVaan United States Patent COLLAPSIBLE DRILL BIT ASSEMBLY METHOD F DRILLING Walter H. De Vaan, 745 Mountain View,

, Monrovia, Calif.

Filed Dec. 3, 1957, ser. No. 700,447

4 claims. (cl. 17e-25s) fice 2 Y serted through the casing to continue the drilling operation;

Figure 4 is an enlarged view in vertical section through a collapsible drill bit in accordance with this invention, showing the manner in which the same is mounted upon a drill stern and carries thereon and has associated therewith a casing, the device being indicated in a well bore in drilling operation therein;

Figure 5 is a view similar to FigureY 4 but showing the position of the parts when the collapsible drill bit has been radially contracted in readiness for-removal from the casing;

FigureV 6 is a view in vertical section, with a portion of a drill stem being shown in elevation together with a portion of a casing mounted thereon, and showing in elevation the locking means by which the stem is secured to the casing, this figure being taken on an enlarged scale substantially upon the plane indicatedby the section line 6-6 of Figure 2; e

Figure 7 is a view in vertical section substantiallv upon the plane indicated by the sectionlline 7--7 of Figure 6 of operation by the provision of means preventing gravel and dirt dislodged from the bore of a well from dropping into the Vbore below thedrill bit or adjacent the same.

A further object of the invention is to provide a method and apparatus for rotary drilling wherein a well casing is installed simultaneously with the drilling operation and without interruption of the latter. s

Still another object ofthe invention is to provide an apparatus and method in accordance with thev preceding objects which will enable the driller to drill a stem downward, break ol and add a new stem and casing section to the top of the string and continue drilling without the necessity for removing the drill` bit ffromthebottom of the hole.

Another object of the invention is to provide a method and apparatus Vfor rotary drilling whereby a casing may be carried by, `secured to and rotated with a drill string 4for insertion into a well bore therewith together with means for sealing the lower end of the casing against the `inlet of fluid therein, and whereby the circulating drilling uid sha'll be down the drill string and drill bit and up the exterior of the casing between the same and the wall i vof the bore.V y 1 A still further important object of the invention is to provide a method andapparatu's in accordance with the immediately' preceding object whereby a casing may be inserted: into and'cemented in"a wellfb'ore without the necessity for withdrawing thedrilling string during this operation; and whereby whenthecasing has been inlserted in a well bore` to the desired depth the ,drill bit may be collapsed and withdrawn to thereby leave theV lcasing'in place. v .f

`These together with other objects andY advantages which will4 become subsequently apparent reside in'the details ,of construction' yand operation' `as j more fully Vhereinafter descrilged and claimed, reference beingnhadgto the accompany drawings' forming -av part hereof, wherein like numeralsrefer to like parts throughout, and in which:

Figure :l is a view,V in vertical section, parts being broken `a'rrcewitl'rconventional practice;

` Figure 2 Ais aV view similarto Figure 1 'but showing a rotary `drill in accordance `withthis invention and with a teasing mounted'upon and carried by and rotated with the e ldrill string/and the collapsibletdrill bit; g

'60 away, and showingV a method of rotaryfdrilling in jaccordrin :forderrto permit; a:monventional"drillingabitatoY befinff.

r resume drilling operations.

substantially upon the plane indicated by the section line 8-8 of Figure 6 and showing in dilerent positions, a clutch 'means for locking the casing section to a drilling stem section; Y

Figure 10 is an exploded perspective view of a portion of the locking means by which the casing section is secured to the drill stem section; and

Figure l1 is an exploded. perspective view, parts being broken away and shown in section, of a fastening means for securing and locking together adjacent sections of a drill stem to prevent separation of the same during reverse rotation of the drilling string.

Figure l illustrates in vertical section the method in accordance with conventional drilling operations wherein a bore 10 has been drilled into a formation by means of a drill stem 12 having upon the lower end thereof a conventional cone-type roller cutter bit 14. As will be understood, the drill string 12 is operated by the usual rotary, not shown, at thesurface of the ground and drilling fluid is circulated therethrough, this being down the drill stem and drill bit, and then upwards in' the bore between the drill stem andthe wall of the bore 10. In such drilling operations, when'it is necessary to add another section to lthe top of the drilling stem 12 in order that the bit 14 may be advanced downwardly to further deepen the hole -10, it is necessary to lift the drill stem so that the drill bit is raised above the bottom of the hole in order to remove `the kelly therefrom, attach an additional section of drill stem, then lower the same and'reapply the kelly and then During this operation, especially when drilling through formations which are of a loose gravel or rock character, it frequentlyoccurs that when the' drill bit is raised for this purpose, rock or gravel drops tot the bottom of the hole therebeneath.

When the drill `stem is again lowered to resume drilling operations, it is then necessary for the drill bit to either break and pulverize -this'graveL lrock or other matter which has dropped into the bottom of the well bore in order that the same maybe removed by the circulation `Yof the drilling lluid which was discontinued in order to permit the d rill stern to be raised for adding anothersection thereto, or'itfissometimes necessary to remove the added section of vthe drill 'stem in order to'lower the drill bit upon the foreign matter falling intolthebottom of the hole and drill through the same. Frequently, the above-mentioned,difliculty will occasion-a considerable loss ottime tothe driller, will sometimes result inY losing ya large part of the hole duetothegfallingLofgrocks lor Y other material into the bottom of the hole; or the rocks falling alongside of the drill bit may even wedge the same and further interfere with the drilling operation.

In accordance with the present invention there isprovided a means and a method which will overcome the above disadvantages by preventing the possibility of rocks -fal-ling into the bottom of the hole when a new sec *Y tion is added to the drilling stem.

Figures 2 and 3 illustrate a method of rotary drilling in accordance with the present invention, Figure 2 showing a radially expansible and contractible drill bit 16 secured to the end of the above-mentioned drilling stem 12, the drill bit in drilling position being radial-ly expanded, while in Figure 3 the drill bit is shown in its radially contracted position. Also shown in'Figures 2 and 3 is `a string of casing 18 which surrounds and is locked to the drilling stem 12 for rotation therewith for Va purpose to be subsequent-ly set forth. The lower end of this casing rests upon and is sealed to the drill bit 16 in such a manner las to prevent the passage of drilling uid into the open lower end of the casing, the casing being of a lesser external diameter than that of the expanded.drill.bit.16. Y,

`Witlrthe casing lsecured to the drilling stem and drill bit as set forth hereinafter, the normal drilling operation is performed to thereby produce the bore 10, drilling fluid being circulated down through the drill string and drill bit, and then up about the side of the casing and between the same and the wall ofthe bore as will be apparent from Figures 2 and 3. In this operation, it is obvious that the casing which is only slightly smaller than the diameter of the well bore 10, would prevent any gravel or rock through which `the drill bit passes from falling into the bore and getting below the drill bit. When it is desired to add a section to the drill stem and casing, in order to continue drilling to greater depths, the rotation of the drill stem and the casing is stopped, with the drill bit resting on the bottom of the bore, the fluid circulation is stopped, the kelly is removed, a new section of drill tern and casing are added to the drill stem and casing i12 and 18 respectively, the kelly lis again attached, circulation of drilling iiuid and rotation of the stern and casing is then resumed and drilling operations continued. l

When the casing has been inserted into the bore to a .desired depth therein, the-casing is unlocked from the drill string and the bit is collapsed and then withdrawn through :the casing which has then dropped to the bottom of the hole in the'manner suggested in Figure 3, after which a conventional drill .bit of any conventional .design but of smaller diameter than the internal diameter of the casing 18 may then be connected to thedrilling stem 1t), introduced into the bore through thecasing and the bore may be then continued downwardly below the easing with a reduced diameter.

The novel apparatus in accordance with `this invention yand one adapted to perform the novel rotary method of this invention consists of a collapsible drill bit 16 of a construction shown especially in Figures 4 and 5; a drill stem 'lower section 29 of special constructionftogether with a means for mounting upon the collapsible bit,v the `lower casing section 18, which mounting means'is indi- 'cated' generally by the numeral 22 yand which comprises a connecting sub; together'with a locking-means for detachably securing Vthe casing`1'8 to 'the drill stem lower section 20, this locking means `Vbeing designated gen- "erally by the numeral 24 and being 'shown in detail in :Figures 6-l0; together with a drill stem section locking frneansdesignated generally rb'y'thenurneral 26; and shown especially in Figure ll, Vfor securing the sections ofthe -drill stem together against relative rotation especially during reverse rotation of a drill string.

Referring now specifically to'Figures 4 andS itwill be seenthatthe Ecollapsibledrill bit `16 consists of Asections 30 and 32 carrying at their lower ends conventional types of roller cone cutters 34. The two sections are pivotally connected together intermediate their ends and at opposite sides thereof as by hinge or pivot pins 36 so that their lower ends together with the cone roller cutters may move towards or from each other upon pivoting of the sections, thereby permitting the cutting surface of the drill bit to be radially expanded or contracted as desired. At their upper ends, these sections are externally tapered and threaded as at 37 and deine an axial bore therebetween as at 38. Below their pivot pins 36 the two sections are provided with complementary opposed lateral recesses 4t) for a purpose to be subsequently set forth.

In order to support the drill bit 16 there is provided a pipe or arbor 42 which is externally threaded as at 44 at itS upper end for the reception of a pair of lock nuts 46. The arbor extends through the bore 38 formed upon the interior of the two sections 39 and 32, and at its lower end is provided with an outturned Ilateral flange 48 loosely received in the lateral recesses 40. As will now be apparent from Figures 4 and 5, the arbor 42 has a limited axial movement in the bore 38 of the drill bit 16, this movement being limited zby the travel permitted the anges 43 in the lateral recesses 40.

Continuing to refer to Figures 4 and 5 it will be seen thatthe sub or mounting means 22 comprises a cylindrical body of lesser diameter than that of the drill bit 16 in the radially expanded position of the latter shown in Figure 4, and of substantially the same diameteras that of the drilling stem 12. This mounting means or sub has a tapered internally threaded bore 50 opening upon its lower surface and which is complementary to and receives the externally threaded portion 37 of the drill bit. The arrangement is such that as the drill bit is moved in screw-threaded engagement upwardly in the bore 50, the upper ends of the sections 30 and 32 will be drawn together causing radial expansion of the lower end of the Vprevent further downward movement of the arbor 42 and drill bit as will be apparent from Figure 5.

At its extreme upward end, the sub 22 is provided with Vinternal threads 56 adapted to engage Acomplementary threads 58 carried by the lower drill stern section 20 to thereby :detachably lock these parts together.

It will thus be apparent that the mounting means 22 serves as a connector whereby the drill bit and the arbor 42 carrying the same are detachably coupled to the lower end ofthe drill stem .through the drill stem secto therebyefect the radially expanding and radially con-v tion' 2li in such a .manner as to permit a limited vertical travel of the dril-l bit with respect to the mounting means tracting operation of the drill bit.

Referring .now to Figure 1l there is discloseda manner by which each of the drill stem sections and the mounting means 22 are detachably locked together against -relative rotation and against loosening' of the screw- Vthreaded connections upon reverse rotation of the drilling stem. Although Figure l1 discloses this locking means applied to the connection between the lowermost drilling stem section 20 and the mounting means 22, it

fwill be :understoodthat the same type of lockingrmeans Vmay be secure/dito each and everyonef the drill stern sections. A l

As willbe apparent vfrom this ligure, the-adjacent surfaces of the two sections are provided with apslightly `{saw-toothed engaging surface 60. j In addition, there are provided vertically aligned complementary slots or grooves 62 and 64 in the two sections for the reception of locking keys to thereby prevent relative rotation between the two sections. Y n

A resilient band 66 is provided having secured upon its interior surface a plurality ofkeys 68. .Y Each key 4is adapted tobe received in a pair of vertically aligned slots 62 and 64 whenthe two drilling stem sections 20 and 22 areproperly screwed together. The band 66 is of a resilient nature so that the samevwill tightly grip the two `sections and 22 and force and retain the keys 68 into the slots 62y and 64 previouslymentioned.,` YAs each sectionis added to the drill stem, one of these locking means 26 is placed in position,'while when thel drill stem is,.withdrawn from the bore, each locking member 26 is in turn removed before the associated stem sections maylbe uncoupled from each other.

@Referring next to Figures 2,- 4 and 5, it will-be seen that the lower open end of the casing 18 is sealed to the 'drill bit 16 in such a manneras to prevent the passage of 6 able therein are'plungers 92 which project outwardly from the drillstein and into'engagement' with the shoes 76 vand Y78. Underthe pressure of the drilling uid when ycirculated through the drill stem as indicated in arrows in Figure 7, the plungers 92 are moved outwardly and thus -in turn force the shoes outwardly against their return drilling fluid tothe interior of the casing. `For this purpose v A there is provided a packing member 70 in the form of a Figure 5 with Figure 4. Thus,` a fluid tight seal is established between the interior of the casing 18 and the exterior of the drilling stem at the drill bit by means of the sub or mounting means 22. It will be observed that the conical surface 72l is such that the lower end of the sub 22 will pass downwardly along the same and wedge the sealing ring outwardly between thesub and the casing.

As previously mentioned, locking means 24 are provided between the drilling stem and the casing to lock the casfing to the stem for rotation and to secure the casing to the stem. Any desired numbervof these locking means may be employed, the construction and operation of one such means being illustrated in detail and disclosed in this application. Y

Referring now especially to Figures 6-10 it will be seen that the locking means consists of a pair of semi-cylindrical sleeves 76 and 7-8 which vare complementary to each other and which are disposed between the stem 12 and Y the casing 18. These sleeves constitute shoes which are radially expansiblel and contractible as set forth hereinafter. l Upon the exterior surface these sleeves have inset any suitable clamping means such as the slips 80 for frictional gripping engagement against the internal surface of the casing sections 18 when theslroes are radially expanded.V Attheir upper and lower edges, the shoe sections are provided with annular grooves 82 fo-r receiving resilient split Yrings 84 which thereby yieldingly urge the shoes into their radially contracted position in which they 'are out ofV engagement with the casing 18. l

Actuating meansV are'provided for insuring radial expansion of the shoesointo gripping engagement with the casing. This actuating means comprises an vinitialv actuatv ing means adapted to initially place theshoes in engagement'with the, casing section together with a further or nal actuating means utilizing the rotation of the drill stem,1to complete the final outward movement of the shoes and perfect their locking engagement with the casing. y

springs 84 until the shoes are in engagement with the casing 18. l 1 y The adjacent surfaces of the drill stem `and of the shoes are provided with complementary longitudinally extending clutch recesses 94 and 96 whose surfaces are inclined to each `otherat 'a slight angle as will be apparent from Figures 8 and-9, and clutch rollers 98 are received in these recesses and by engagement of their opposite ends with the upper and `lower surfaces ofthe two sets of recesses, serve to mount and support the shoes upon the drill stem. f The arrangement is such, as will be seen by comparison of Figures 8and 9 that when the drill stem is Irotated in a clockwise,` direction, the relative movement of the rollers 98 in the two sets of recesses 94 and 96 will force the shoes outwardly and causetheir slips `80 to firmly and securely engage the casing 18A and lock the `same to the stem 12 for rotation therewith. However, when the rotation of the djrillstem is reversed, the rollers are'fmoved to the other ends of the two sets of clutch cavities', thereby permitting the shoes to move inwardly under the influence oftheir return springs 84 and thus radially contract `the shoes and disengage the same from the casing. `From the foregoing, it is believed that the operation of the device will be readily apparent. When a casing has been carried by Ythe drillstem to a desired location in a well bore, and the casing can readily move in the well bore since the circulation of the drilling uid upon the exterior of the casing and within the well bore maintains A an annular space or clearance between the bore and casing, the casing may be cemented in place by merely running'cementing material Vthrough the drilling stern and drill bit and up the exterior of the casing and permitting this cement to set or harden.v Thereafter, the drill stem is reversed in rotation cau-sing the joint between 37 and 50 to unscrew from the position shown in Figure 4 to that shown in Figure 5. As the drill bit is lowered from the sub 22, the drill bit will collapse either under its own weight, or by the upward pull of the sub 22 through the nuts 46 and the arbor 42. and ange 48 in the recess 40. Thereafter, the collapsed drill bit and the drill stem can be moved upwardly through the casing sections and removed from the well bore. As soon as the drill bit is collapsed, however, the casing will unless cemented, of its own weight drop to the bottom of the well bore as shown clearly in AFigure 3 as compa-red to the position of Figure 2. In this position, the casing prevents any ingress of gravels, rocks or foreign matter below the same. A conventional drill bit, but smaller than the diameter of the casing can then be attachedto the drill stern 12 and lowered through the casing and drilling operations resumed and the hole ex? tended downwardly as much as desired. v

As shown in Figure 7, the drill stem 12 at each of the locking devices 24 is provided with sets of laterally extending bores 90 which communicate with the hollow in-l It will be observed that by this method of drilling an this apparatus, it is not necessary to lift the drill bit 'to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed. l

What is claimed as new'is as follows: l. A rotary drillingapparatus comprising a drill stem and a radially expansible drill bit thereon, a casing surrounding said stern, said drill bit beingiradially 'expansible to a diameter greater than that of said casingp'for drilling and collapsible to a diameter less than that ofsaid casing 'for withdrawal through the latter, means for locking said casing to said drill stern for rotation thereby, said locking means including shoes carried by said drill stern and operable to engage said casing, actuating means for vcausing locking engagement of said shoes with said casing, said actuating means comprising initial operating means actuatable by the pressure of the drilling fluid to move vsaid shoes into engagement with said casing, and further operating means actuatable by rotation of said drill stern to complete Vthe movement of said shoes into nal locking engagement with said casing.

2. A rotary drilling apparatus comprising a drill stem land a radially expansible drill bit thereon, a casing surrounding said stem, said drill bit being radially expansilble to a diameter lgreater than that of said casing for drilling and collapsible to a diameter less than that vof said casing for withdrawal through the latter, means for locking said casing to said drill stem for rotation thereby, said locking means including shoes carried by said drill stem and operable to engage said casing, actuating means for causing locking engagement of said shoes with said casing, said actuating means comprising complementary relatively inclined clutch recesses in said d-rill 'stem and shoes, clutch rollers each received in both said recesses and operable upon relative rotation of said stem and shoes to move the latter outwardly into final locking engagement with said casing.

3. A rotary drilling apparatus comprising adrill stem and aradially expansible drill bit thereon, la casing surrounding said stem, said drill bit being radially expansible toa diameter greater than that of said'casing for drilling ,and collapsible to a diameter 'less than that of said casing for withdrawal through the latter, means for locking said casing to said drill stem for rotation thereby, said locking means including shoes carried by said drill stem and Voperable to engage said casing, actuating means for causing locking engagement of said shoes with said casing,A said actuating means comprising initial operating means actuatable bythe pressure ofthe drilling lluid to move said shoes intoengagement with said casing, and a f urther operating means comprising complementary relatively inclined clutch recesses inA said drill stem and shoes, clutch rollers each received in both said recesses and'operable upon relative rotation of said stern and shoes to move the latter Aoutwardly'into tinal locking engagement with said casing.

4. The combination of claim 3 wherein 'said clutch rollers comprise means for supporting and mounting said shoes on said stem.

References Citcdin the tile of this patent UNITED STATES PATENTS Bade Sept. 24, 

